Stripping device for punch presses and the like



Oct. 17, 1933. LELAND 1930,762

STRI PP-ING DEVICE FOR PUNCH PRESSE S AND THE LIKE Filed July 11, 19322' Sheets-Sheet l Fig.1-

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his ATTORNEY.

Oct. 17, 1933. G. H. LELAND STRIPPING DEVICE FOR PUNCH PRESSES AND THELIKE Filed July 11, 1932 2 Sheets-Sheet 2 his ATT0RNY Patented Oct. 17,1933 UNETEB STATES riiijh.

s'rniPPING DEVICE FOR PUNCH PBESSES AND THE LIKE George H. Leland,Dayton, Ohio, assignor of cne half to The Leland Electric Company,

Dayton, Ohio, a corporation of Ohio Application July 11, 1932. SerialNo. 621,943

17 Claims.

This invention relates to a stripping device for punch presses and thelike. In the operation of a punch press it frequently happens that theblank, or part which has been severed, will adhere to the face of thepunch and be withvn from e die when the punch is retracted, this beingparticularly liable to happen when a liquid cutting compound is appliedto the face of the material from which the blank is to be cut. Further,in many cases, and especially in the case of progressive die work, thepunch is provided with a pilot, such as a stud or pin, adapted, to entera previously formed opening in that part of the material which is to besevered, for the purpose of properly alining the same with the punch anddie. Such a pilot necessarily fits snugly within the opening and has atendency to withdraw the severed blank from the die when the punch isretracted. This withdrawal of the blank from the die is objectionable inany case but it is particularly objectionable in the case of automaticpresses as it will usually clog the operation of the press and make itnecessary to shut down the press and remove the displaced blank. In aneffort to prevent the blank adhering to the punch or pilot it has beencustomary heretofore to utilize a stripping device comprising springactuated plungers or pins mounted in the punch and adapted to be movedinto the punch by engagement with the stock as the punch moves towardthe stock and to be projected by the springs as the punch is retracted.In such a device the springs must be of sufficient strength to strip 1the blank from the face of the punch and from the pilot but they mustnot be strong enough to istort the blank or'hold it so tightly againstthe die that the pilot will be unable to move it into alinernent withoutdistorting the opening through which the pilot operates. This requires anicely regulated tension on the spring which is difficult to secure andto maintain and as a result such spring actuated stripping devices havenot been satisfactory in operation.

One object of the present invention is to provide a positive strippingdevice which will operate without the use of springs to strip the blankfrom the face of the punch and from the pilot.

A further object of the invention is to provide such a stripping devicein which the plunger or plungers will be retracted before they engagethe stock or material from which the blank is to be cut, thus avoidingany possible interference with the action of the pilot.

A further object of the. invention is to provide such a device in whichthe stripping plunger will be retracted duriru the initial portion ofthe downward movement of the punch and will be retained in its retractedposition until the punch begins its upward movement and will then bepositively caused to project beyond the face of the punch to hold theblank in the die while the punch and pilot strip themselves from theblank in receding.

A further object or" the invention is to provide such a device whichwill be simple in its construction and operation and which may beapplied to a punch press without material modification in theconstruction thereof.

Other objects of the invention will appear as the device is described indetail.

In the accompanying drawings Fig. 1 is a vertical sectionalv View takenthrough a stripping device embodying my invention and showing the sameapplied to a punch press with the punch in a partly lowered position;Fig. 2 is a vertical section taken through the stripping device showingthe position of the parts as the punch begins its upward movement; Fig.3 is a section taken on the line 3-3 of Fig. 1; Fig. 4 is a sectiontaken on the line -i=i of Fig. 1; Fig. 5 is a top plan view of thefriction device; and Fig. 6 is a side elevation of the friction device.

In these drawings I have illustrated one embodiment of my invention andhave shown the same as applied to a punch press of conventionalconstruction but it will be'understood that the device may take variousforms and may be applied to punch presses of various kinds withoutdeparting from the spirit of the invention.

I have illustrated only so rnuchof the punch press as is necessary foran explanation of the application of t e invention thereto and, as hereshown, this press comprises a bed plate 6 on which is mounted a die 7.Mounted for vertical movement on the frame of the press is a ram 8 whichmay be operated in the usual or any suitable manner. Supported by thisram is a punch 9 which, in the present instance, is carried by a plate10 which in turn is secured to the ram 8, the rain and the plateconstituting the support for the punch. The punch is provided with apilot ll projecting below the operative face thereof and adapted toenter an opening 12 previously formed in the part of the material whichis to be severed, a group of severed blanks being shown in the die at 13in Fig. 2.

The punch is provided with one or more, in the present instance three,guideways 14, which, ill) as here shown, comprise vertical bores havingtheir upper portions enlarged, as shown at 15. Slidably mounted in therespective guideways are plungcrs or stripping pins 16 which are of sucha length and so arranged that their lower ends may project below thelower or operative face 0:" the punch to strip the blank therefrom. Inthe present arrangement the supporting plate 1-? is provided with arecess 1'? arranged in line with the guideways in the punch and intowhich the up er ends of the plungers extend.

Connected with the plungers is a'suitable actuating device which, in theconstruction here shown, comprises a rod 18 which extends through thesupporting plate 10 and ram 8 and is capable of vertical movement withrelation thereto. The lower end of this rod extends into the recess 17and is connected with the plungers 16. As here shown, the rod hasrigidly secured to its lower end a head or spider the laterallyextending parts of which are slotted to embrace the upper ends of theplungers 16, these plungers having enlarged upper ends provided withcircumferential grooves 20 to receive the slotted portions of thespider. The grooves 2-3, are of a width substantially equal to thethickness of the d parts of the spider so that the plung- 0t" ers willmove with the spider. The spider is of the depth of the recess athickness less than 1'5, the upper part of the recess being preferablyprovided with extensions 21 to receive those parts of the plungers whichproject above the spider. at will be apparent, therefore, that theplunger-s and the punch are capable of relative movement, this relativemovement being controll d by the contact of the spider 19 with the upperand lower walls of the recess 1'7, the lower wall of the recess beingformed by the top of the punch 9. The amount of movement thus erinittedis such that when the spider 19 is in contact with the lower wall of therecess the plungers will project below the operative face of the punchfar enough to strip the blank from the pilot 11, and when the spider isin engagement with the upper wall of the recess the plungers will bewithdrawn into the guideways 14 and their lower ends will be eitherflush with or slightly above the operative face of the punch. heplungers are projected and retracted by holding the actuating rod 18against movement with the punch during a portion of each movement of thelatter. This is preferably accomplished by applying to the actuating roda friction device which will retard its movement atthe beginning of eachmovement of the ram. Thus when the ram begins its downward movement therod will be held against movement until the upper wall of the recess hasengaged the spider 19, thus causing the plungers to be retracted and tobe retained in their retracted positions as the rod is then moveddownwardly by the ram against the action of the friction device. Whenthe ram begins its upward movement the plungers will be held againstmovement, and in contact with the blank, until the spider has engagedthe lower wall of the recess and will then be carried upward with theram and the punch. The friction device may take various forms but it ispreferably carried by a fixed part of the press arranged above the headof the ram. As here shown, the frictional device is carried by a framemember comprising two parallel bars 22 rigidly secured at their ends toother frame members 23 mounted on the press. The friction device itselfcomprises a hollow member 24, preferably substantially cylindrical inshape, which is arranged between the bars 22 and has at its upper end anintegral plate 25 which overlaps the upper edges of the bars andsupports the cylindrical member thereon.

Cross bars 26 engage the lower edges of the supporting bars 22 and areconnected with the respective end portions of the plate 25 by bolts 27,thereby enabling the cylindrical member 24 to be rigidly clamped inposition on the supporting bars 22. The cylind ical member 2-: is of aninternal diameter substantially greater than the diameter of theactuating rod 18 and mounted in this cylindrical member and about theactuating rod is a series of friction elements 23, suitable frictionalmaterial 29 being preferably interposed between the friction elementsand the rod. These friction elements have their upper and lower edgesbeveled, as shown at 30, and the cylindrical member 24 has at its lowerend an inwardly extending flange 31, the upper surface of which isinclined inwar ly and downwardly to correspond to the inclination of thebeveled lower edges of the friction element. A hollow nut 32 is screwthreaded into the upper end of the cylindrical member 24, surroundingthe rod 18, and has its lower edge inclined or beveled, as shown at 33,to engage the beveled upper edges of the friction el ments. It will beapparent therefore that the tightening down of the nut 32 will cause thetriotion elements to be forced inwardly into firm engagement with theactuating rod 18, the amount of the frictional resistance offered to themove ment of the rod being regulated by the adjustment of the nut 32.

A separate punch supporting plate 10 is usually provided for each punch9 and when punches are changed the supporting plate is removed with thepunch. Likewise a separate stripping device is usually provided for eachpunch and in order that the same actuating rod 18 may be used with aplurality of different punches and their stripping devices I have shownthat rod as formed in two parts, the major portion 18 of the rod beinglocated normally in and above the ram 8 and a lower part 34 beingsecured to the spider l9 and located in the supporting plate 10. Theparts 34 of the several stripping devices are identical in constructionand of the same diameter as the upper part 18 of the actuating rod andare adapted to be rigidly secured thereto. As here shown, the abuttingedges of the two parts of the rod are provided with tongue and groove,as shown at 35, to properly aline the same, and both parts of the rodare hollow. A bolt 35a extends through the upper portion 13 of the rodand has its lower portion screw threaded into the part 34 of the rod,and the head 36 of the bolt engages the upper end of the part 18 of therod, so that by tightening down the bolt the two'parts of the rod may berigidly connected one to the other so as to constitute in eiiect asingle actuating device. 7 While I have shown and described oneembodiment or my invention I wish it to be understood that I do notdesire to be limited to the details th reof as various modifications mayoccur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desireto secure by Letters Patent, in:

1. In a punch press or the like comprising a ram an a punch carriedthereby, a blank stripping plunger movably mounted in said punch andadapted to project beyond the lower face thereof, and means controlledby the movements l i-O of said ram to cause said plunger to be retractedwhen said ram begins its downward movement and to be projected when saidram begins its upward movement.

2. In a punch press or the like comprising a ram and a. punch carriedthereby, a blank stripping. plunger movably mounted in said punch andadapted to project beyond the lower face thereof, and means. actingindependently of the material on which said punch operates. to causesaid plunger to be retained in its retracted position during thedownward movement of said ram and to be projected during the initialupward movement of said ram.

3. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die, a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plunger to project beyond theoperative face of said punch, and friction controlled means acting onsaid plunger to retard the movement of said plunger with said punch.

i. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die, a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plunger to project beyond theoperative face of said punch to strip the blank therefrom, a device tocontrol the position of said plunger with relation to said punch, andmeans acting on said device to cause said plunger to be projected duringthe initial movement of said punch from said die and to be retractedduring the movement of said punch in the other direction and before saidplunger engages the material to be punched.

5. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die, a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plunger to project beyond theoperative face of said punch to strip the blank therefrom, a device tocontrol the position of said plunger with relation to said punch, andmeans acting on said device to retard the movement of said plunger withsaid punch during the initial portion of the movement of said punch ineither direction.

6. In a punch press or the like comprising a punch and a die, and meansfor moving said 'punch toward and from said die, a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plun er to project beyond theoperative face of said punch to strip the blank therefrom, and meanscontrolled by the movement of said ram to hold said plunger againstmovement with said punch during the initial portion of each movement ofsaid punch and for causing said plunger to move with said punch duringthe remaining portion of each movement of said punch.

7. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die, a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plunger to project beyond theoperative face of said punch, a device connected with said plunger formovement therewith, and friction means acting on said device to. retardthe movement of said device during av portion of each movement of saidpunch.

8. In a punch press or the like comprising a reciprocatory ram and apunch carried by said ram, a plunger mounted in said punch, said plungerand said punch being capable of relative movement to cause said plungerto project beyond the operative face of said punch, a device connectedwith said plunger and having means for causing it to move with said ramduring a portion of the movement of said ram, and a friction devicemounted on a fixed part of said press and engaging the first mentioneddevice to retard the movement thereof with said ram.

9. In a punch press or the like comprising a reciprocatory rain and apunch carried by said ram, a plunger mounted in said punch, said plungerand said punchbeing capable of relative movement to cause said plungerto project beyond'the operative face ofsaid punch, a device connectedwith said plunger and having means for causing it to move with said ramduringa portion of the movement of said ram, a friction device mountedon a fixed part of said press and engaging the first mentioned device toretard the movement thereof with said ram, and means for adjusting saidfriction device to vary the frictional resistance offered thereby to themovement of said first mentioned device. 7

10. In a punch press or the like comprisinga die, a punch, a support forsaid punch, and means for moving said support toward andfrom said die, aplunger slidably mounted in said punch, said support having a recess inline with said plunger, a device having a part movably mounted in saidrecess and connected with said plunger, the movement of said supportwith relation to said device being limited by the Walls of said recess,and means for retarding the movement of said device with said supportuntil a wall f said recess engages said part of said device.

11. In a punch press or the like comprising a die, a punch, a supportfor said punch and means for moving said support toward and from saiddie, a plunger slidably mounted in said punch, said support having arecess in line with said plunger, a device having a part movably mountedin said recess and connected with said plunger and having a second partextending upwardly beyond said support, the relative movements of saidsupport and said device being limited by the opposed walls of saidrecess, and a friction device acting on said second part of the firstmentioned device to resist its movement with said support.

12. In a punch press or the like comprising a die, a punch, a supportfor said. punch and means for moving said support toward and from saiddie, a plurality of plungers slidably mounted in said punch, saidsupport having a recess in line with said plungers, an actuating rodslidably mounted in said sup-port, extending above the same and havinglaterally extending parts arranged for limited movement in said recessand connected with the respective plungers, and a friction devicemounted on a fixed part of said press and acting on said rod to hold thesame against movement with said support until said lateral parts engagea wall of said recess.

13. In a punch press or the like comprising a die, a punch, a supportfor said punch and means for moving said support toward and from saiddie, a plunger slidably mounted in said punch, an actuating deviceslidably mounted in said support, extending above the same, connectedwith said plunger and having means to limit the movement of said supportwith relation thereto, and a friction device carried by said press abovesaid support and engaging said device to resist its movement with saidsupport.

14. In a punch press or the like comprising a die, a punch, a supportfor said punch and means for moving said support toward and from saiddie, a plunger slidably mounted in said punch, an actuating deviceslidably mounted in said support, extending above the same, connectedwith said plunger and having means to limit the move ment of saidsupport with relation thereto, a frame member carried by said pressabove said support, a hollow member mounted on said frame member andthrough which said actuating device extends, a frictional elementmounted in said hollow member, and adjustable means for pressing saidfrictional element against said actuating device.

15. In a punch press or the like comprising a die, a punch, a supportfor said punch and means for moving saidsupport toward and from saiddie, a plunger slidably mounted in said punch, an actuating rod slidablymounted in said support, extending above the same, connected with saidplunger and having means to limit the movement of said support withrelation thereto, a frame member carried by said press above saidsupport, a cylindrical member mounted on said frame member, and throughwhich said actuating rod extends, a plurality of friction elementsmounted in said cylindrical member about said rod and each having itsupper and lower edges beveled, said cylindrical member having aninclined surface to engage the beveled lower edges of said frictionelements, and a nut screw threaded into the upper portion of saidcylindrical member and having an inclined surface to engage the upperbeveled edges of said friction elements.

16. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die, a device mounted in saidpunch for movement therewith and adapted to be projected beyond theoperative -face thereof to strip the blank from the punch, and meansacting on said device to retain the same in its retracted positionduring the final portion of the movement of said punch toward said dieand to hold said device against movement with said punch during theinitial portion of the movement of said punch from said die and thuscause said device to hold the blank against movement with the punch.

17. In a punch press or the like comprising a punch and a die, and meansfor moving said punch toward and from said die,; a plunger mounted insaid punch and movable therewith, said punch and said plunger beingcapable of relative movement to cause said plunger to project beyond theoperative face of said punch, and means acting on said plunger to retardthe movement thereof with said punch during the initial movement of saidpunch in both directions.

GEORGE E. LELAND.

